1. Field of the Invention
The opportunity to provide novel genetic capabilities to microorganisms and cells of higher organisms has opened up broad avenues to new capabilities. In one arena is the concern with various agents that are utilized for their cytotoxic effect. For example, many compounds used in agriculture are directed to the killing of pests, weeds, or the like. In many cases, these compounds can have a relatively long residence time or extended residue.
In many situations, one wishes to distinguish between species which are to be retained and species which are to be killed. For example, it is frequently desirable to selectively kill weeds while having minimal adverse effect on crops. For the most part, many of the broad spectrum herbicides have a significant adverse effect on the crop, so that their use is primarily limited to preemergent use or careful postemergent application.
It is therefore of great interest to be able to modify viable cells to make them resistant to stresses such as cytotoxic agents.